Ultrastructure et cytochimie des cellules superficielles du nucelle de<i>Thuya orientalis</i>L. (=<i>Biota orientalis</i>(L.) Endl.) au moment de l'émission de la goutte micropylaire

Seridi, Ratiba; Chesnoy, Liliane

doi:10.1080/01811797.1986.10824693

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…The possible function of the lignification of integument cell walls has been discussed previously by Carafa et al (1989). Secretion of the micropylar drop has been compared to the phenomenon of guttation (McWilliam 1958;Owens et al 1981) or to nectar secretion (Moussel 1980;Knox 1984), but Seridi and Chesnoy (1986) are of the opinion that the histological organization of the nucellus is not analogous to either that of the hydathodes or that of nectaries, whose functional efficiency implies the nearness of xylem or phloem vessels. Our observations are in agreement with those of Seridi and Chesnoy since there was no similarity between the structure of the Welwitschia mirabilis nucellus and those of the hydathodes and nectaries.…”

Section: Discussionmentioning

confidence: 99%

Anatomical observations on the nucellar apex of Wellwitschia mirabilis and the chemical composition of the micropylar drop

Carafa¹,

Carratù²,

Pizzolongo³

1992

Sexual Plant Reprod

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Summary.In the young ovule of Welwitschia mirabilis the nucellar apex is dome shaped and starch begins to accumulate near the female gametophyte. With the degeneration of the cells of the nucellar apex, a pollen chamber is formed, which contains the micropylar fluid. Starch storage increases considerably in the upper part of the nucellus. Pollen drop emission is not a rhythmic process, and pollination does not produce the rapid withdrawal of droplets. The micropylar drop consists almost entirely of sugars, uronic acids and a very small amount of free amino acids and enzymes. The mechanism of micropylar drop secretion and its probable role in the process of pollination is discussed.

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Section: Discussionmentioning

confidence: 99%

Anatomical observations on the nucellar apex of Wellwitschia mirabilis and the chemical composition of the micropylar drop

Carafa¹,

Carratù²,

Pizzolongo³

1992

Sexual Plant Reprod

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“…Before the pollination drop appears, a part of the nucellus cells will degrade in the form of PCD in P . orientalis 40 , similar to many species 7,11,12,41 . Some researchers consider the degradation products to induce or participate in the formation of pollination drops 41 .…”

Section: Discussionmentioning

confidence: 66%

“…As an indispensable part of pollination mechanism of female cone, the pollination drops of living gymnosperm lineages are involuted ovular secretions from nucellar tip cells. Some phenomena have been observed in nucellar cells, for example, the fluctuating cell membranes, agminate high-density electrons, the extensive and active Golgi apparatus and endoplasmic reticulum during secretion, and the accumulation of starch grains before secretion 10–12,40,41 . These phenomena indicate that secretion of the pollination drop may be related to transmembrane transport, and the transport efficiency of water and small solutes in plants is closely related to aquaporins (AQPs) 42 .…”

Section: Discussionmentioning

confidence: 99%

De novo assembly of the Platycladus orientalis (L.) Franco transcriptome provides insight into the development and pollination mechanism of female cone based on RNA-Seq data

Zhou

Chen

Wang

et al. 2019

Sci Rep

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For seed-bearing plants, the basis of seed and fruit formation is pollination. The normal progression of pollination is through advances in continuous signal exchange and material transfer, which occur mainly in female reproductive organs; thus, the molecular mechanism of development in female reproductive organs is vital for understanding the principle of pollination. However, molecular biology studies on the development of female cones related to pollination are rare and unclear in gymnosperms, especially in Cupressaceae. In this study, Platycladus orientalis , a monotypic genus within Cupressaceae, was chosen to examine female cone transcriptomes at pre-pollination and pollination stages by Illumina paired-end sequencing technology to de novo sequence six libraries with 3 biological replicates. These libraries were used to construct a P . orientalis transcriptome database containing 71,669 unigenes (4,963 upregulated unigenes and 11,747 downregulated unigenes at the pollination stage) for subsequent analysis. Based on the annotations and expression levels, the functions of differentially expressed unigenes and enriched pathways between the developmental processes of female cones were analysed to detail the preliminary development and pollination mechanism of the female cone. Targeted investigations were specifically performed to determine the elementary mechanism of secretion and functioning of the pollination drop, a vital ovule secretion at the pollination stage. Ultimately, the expression of 15 unigenes selected between two stages were further assessed and confirmed using qRT-PCR, which demonstrated reliable data and significant differences in the expression profiles of key genes. As one of the largest available transcriptomic resources of this species, the database is constructed to prospectively adapt to the physiological and genomic data of woody plants. This work provided the first transcriptome profile of P . orientalis female cones at different developmental stages, and will promote the illumination of the pollination mechanism of P . orientalis , and will serve as the basis for in-depth genomic study in the Cupressaceae family. This initiative will arouse the interest and attention of scholars and pave the way for future studies.

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“…Ultrastructural studies to determine the site of the pol- Chamaecyparis (Cecchi-Fiordi and Maugini, 1977), Picea (Owens, Simpson, and Caron, 1987), Platycladus (Seridi and Chesnoy, 1986), Cephalotaxus (Seridi-Benkaddour and Chesnoy, 1991), Taxus (Chesnoy, 1993), and Cedrus (Takaso and Owens, 1995b). We add Sequoiadendron to this list and describe other features of the integument, chalaza, and bract.…”

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confidence: 99%

Ovulate cone, pollination drop, and pollen capture in Sequoiadendron (Taxodiaceae)

Takaso

Owens

1996

American J of Botany

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In Sequoiadendron ovules are borne inside the ovulate cone, and pollination drops secreted from these ovules collect pollen. We examined: (I) the relation between ovular position and pollen capture; (2) pollen behavior when in contact with a pollination drop; and (3) ultrastructure of ovules during pollination drop secretion. During wet periods a water sheet forms on the surface of the cone due to bract shape and wettability. Pollination drops persist inside the wetted cone, and pollen capture resumes immediately after drying. Pollen landing on a pollination drop is taken inside the drop and carried into the micropyle when the drop contracts. Several notable ultrastructural features appear in the nucellus, integument, chalaza, and bract lamina during pollination-drop secretion. The abaxial surface of the lamina is covered by a membrane that may contribute to the wettable nature of the surface.

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Ultrastructure et cytochimie des cellules superficielles du nucelle deThuya orientalisL. (=Biota orientalis(L.) Endl.) au moment de l'émission de la goutte micropylaire

Cited by 5 publications

References 12 publications

Anatomical observations on the nucellar apex of Wellwitschia mirabilis and the chemical composition of the micropylar drop

Anatomical observations on the nucellar apex of Wellwitschia mirabilis and the chemical composition of the micropylar drop

De novo assembly of the Platycladus orientalis (L.) Franco transcriptome provides insight into the development and pollination mechanism of female cone based on RNA-Seq data

Ovulate cone, pollination drop, and pollen capture in Sequoiadendron (Taxodiaceae)

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